In my case, no serious issues with the size. But often it would get a laugh and they would show it to their partner the next booth over. Sometimes they would just flip through a page or two and not even bother to stamp it. And airlines never cared.

The only issue I had was that late in its life I spilled a bit of Nyquil on it which made the photo page look like it could have possibly been tampered with. But still they eventually let me through each time.